In a radial direction, twin Screw pumps are not hydraulically balanced and require radial bearings at each end of each shaft. In twin screw pumps, external timing gears and bearings keep the screws from contacting each other or their casing bores and do not rely on pumped fluid characteristics.

Both twin screw and three Screw pumps share many applications including hydraulic services, machinery lubrication, compressor and expander gas sealing and some refinery (heavy fuel, asphalt, vacuum tower bottoms, bitumen) and chemical processing (synthetic fibers, explosives, polyol, isocyanate) applications.

Examples of critical applications include modified twin screw pumps used to handle multiphase flow, i.e., oil well head flows ranging from nearly 100 percent gas to 100 percent liquid including liquid slugs. Three screw pumps find use aboard combat ships for hydraulic services where extremely quiet operation is necessary to avoid acoustic detection. Both twin and three screw pumps are used in medium and heavy crude oil pipelines operating at efficiencies far above centrifugal pumps.

MultipleScrew pumps operate at much higher efficiencies than centrifugal pumps on even moderately viscous liquids. Energy cost savings can be substantial. For example, three screw pumps operating in the 1,000-hp range on heavy crude can save more than $1 million annually in energy cost per three pump pipeline station, a significant amount even though they have lower power than big centrifugals.

More products of pumps

Chemical pumps

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Sweage pumps &Sludge pumps

Multi-stage pumps Slurry pumps

Other pumps

2012-06-07

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